A new genus and species of unenlagiine dinosaur has been identified by paleontologists in Argentina. Named Diuqin lechiguanaeit fills a significant gap in the fossil record of these theropod dinosaurs.
Reconstruction of the life of Diuqin lechiguanae. Image credit: Porphyry et al., doi: 10.1186/s12862-024-02247-w.
Diuqin lechiguanae orbited our planet during the Santonian epoch of the Cretaceous period, between 86 and 84 million years ago.
This species belongs to the Unenlagiine, a subfamily of long-snouted paravian theropods within the family Dromaeosauridae.
“Unenlagiines are predatory dinosaurs from Gondwana that are nested within Paraves, the clade that includes birds and their closest non-avian relatives theropods,” said Dr Juan Porfiri of the Universidad Nacional del Comahue, Buenos Aires, and his colleagues.
“Unenlagiine fossils come primarily from Argentina, where the largest number of specimens and the most complete skeletons have been found, although other material at least tentatively assigned to Unenlagiinae has also been found from Brazil, Chile, Colombia and Antarctica.”
“The Madagascan Small-Body Potentially Volant Theropod.” Rahonavis ostromi it is also often regarded as an unenlagiine, depending on the specific phylogenetic hypothesis used.
“Unenlagiines are most often interpreted as early diverging dromaeosaurids, although other authors instead consider these theropods as a separate paravian clade (Unenlagiidae).”
“They are an important group for understanding the origin of birds because of their close phylogenetic relationship with the Avialae.”
“Unfortunately, however, most species are represented only by fragmentary fossils.”
Diuqin lechiguanaeThe fragmentary but connected postcranial skeleton of was recovered from the Bajo de la Carpa Formation in Neuquén Province, Patagonia, Argentina.
“The specimen was collected from the isthmus between the southeastern shore of Lago Bareales and the northwestern shore of Lago Mari Menuco, in the province of Neuquén,” the paleontologists said.
According to the authors, Diuqin lechiguanae is the first species of unenlagiine dinosaur discovered from the Bajo de la Carpa Formation.
“The Bajo de la Carpa Formation has yielded fossils that collectively represent a diverse and important palaeobiota,” they said.
“The vertebrate remains are abundant and often well preserved and include those of snakes, lizards, turtles, crocodyliforms, unspecified pterosaurs, ornithopods, titanosaurian sauropods, non-avian theropods and birds.”
Diuqin lechiguanae fills a time gap of at least 15 million years in the unenlagiines fossil record (conservatively, 90-75 million years, possibly more).
“The new species adds to the fossil record of South American unenlagiines by filling a significant gap in their temporal distribution,” the researchers said.
“Preserved elements of Diuqin lechiguanae show morphological differences from corresponding bones in other unenlagiine species, such as an additional lamina on the most posterior sacral vertebral neural arch, distinctive paired foramina on the posterior sacral and anterior caudal neural arches, and a humerus with a distally located distolateral deltopectoral crest, and several conditions that occur in between between the humerus of Unenlagia spp. and the extremely large unenlagiine body Austroraptor cabazai.”
“Combined with the multimillion-year stratigraphic gaps between Diuqin lechiguanae and geologically older and younger unenlagiines, respectively, these anatomical differences support the validity of the new species.
“Furthermore, the humerus of Diuqin lechiguanae the type specimen shows two conical tooth marks indicating that the carcass was fed by another tetrapod, possibly a crocodilian, mammal, or theropod (perhaps the megaraptorid represented by a tooth found at the same site, or even another non-enlagin individual, potentially a member of same species).’
Opening of Diuqin lechiguanae reported in a journal article BMC Ecology and Evolution.
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JD Porphyry et al. 2024 Diuqin lechiguanae gen. et sp. nov., a new unenlagiine (Theropoda: Paraves) from the Bajo de la Carpa Formation (Neuquén Group, Upper Cretaceous) of Neuquén Province, Patagonia, Argentina. BMC Ecol Evo 24, 77; doi: 10.1186/s12862-024-02247-w
